Nearly 12 years ago, with the fires still smoldering under the rubble of the World Trade Center, Mayor Rudy Giuliani made a late endorsement. Nine days before the general election to pick his successor, he threw his support behind Michael Bloomberg.

“I am very, very confident that the city would be in absolutely excellent hands in the hands of Mike Bloomberg,” Giuliani said on the steps of City Hall.

Bloomberg, down about 15 points in the polls, professed himself flattered, and said he hoped the backing of America’s Mayor would be “comforting” to voters. It was indeed, and he roared across the finish line to defeat Democrat Mark Green and become the city’s 108th mayor.

In the most basic of ways, we have come full circle. Just as public safety was a defining issue in the aftermath of 9/11, it remains so in 2013.

Or at least it should be. But after 20 years of falling crime, and 12 years without a successful terror attack, many New Yorkers have come to take public safety for granted. They either didn’t know or have forgotten what New York was like when nobody felt safe.

Part of that collective blank spot is not accidental. For the last year, the Democrats who want to succeed Bloomberg have talked about everything except public safety.

When they do talk about the world’s greatest police force, they do it in shamefully derogatory terms. Commissioner Ray Kelly, rightly celebrated as a hero among many New Yorkers for the record-low crime rates and for foiling terror plots, is a bum who deserves to be fired, according to the Democrats.

This is not merely a partisan split. This is a split between the Democrats and planet Earth.

In that sense, the claim by candidate Bill de Blasio that there are “two New Yorks” is, inadvertently, accurate. One New York appreciates what the police have done, and the other doesn’t understand what will happen if the cops are forced to retreat.

By any fair yardstick, it is truly remarkable how far the city has come in 12 years.

The terrorist attack, followed by a national recession and the fear of more attacks, raised serious doubts about whether the city would survive. Those doubts are being answered by a continuing rebound not only in lower Manhattan, but with the creation and rebirth of whole neighborhoods in all the boroughs.

Think of it this way: Every time a restaurant or store opens or an apartment gets renovated, that investment represents someone’s faith in the future. It is a faith born of trust in personal safety.

When that trust spreads to all corners of the city, and when rents hit $3,000 a month in Brooklyn, there is no denying that Gotham is experiencing a new golden age of trust.

But if you are one of the many people who can’t afford such rents, be patient. If a Democrat wins in November, Brooklyn could soon be on sale.

To believe that the cops can be handcuffed with red tape and there will be no consequence is to believe New York could never go backwards. It is also to believe that those who live here are more honest than those who live in Chicago, Philly, Detroit or virtually any other American city.

It is all nonsense, dangerous nonsense. New York is by far the safest big city in the nation because Giuliani and Bloomberg funded a large police force and demanded not only that it catch criminals, but also prevent crimes in the first place.

“First preventers” Bloomberg dubs those formerly called “first responders.” It’s a case where a single word makes the difference between life and death.

It is not the legacy Bloomberg planned for himself, but once he got into office and appointed Kelly, he quickly realized that everything good started with public safety. Giuliani hoped that would happen, and now Bloomberg wants a successor who shares the same understanding.

Until then, the city is up for grabs. In Joe Lhota, the Republicans offer a candidate who knows that public safety is the first civil right. The two remaining Democrats — well, they believe the cops are the problem.

We’ve faced this choice before, and can only hope that, once again, voters are wise enough to choose public safety over appeasement.